Abstract

Background

Aortic aneurysm is an increasingly common vascular disorder with fatal implication.
However, there is no established diagnosis other than that based on aneurysmal size.
For this purpose, serum protein biomarkers for aortic aneurysms are valuable. Although
most of the studies on serum biomarker discovery have been based on comparison of
serum proteins from the patient group with those from the healthy group, we considered
that comparison of serial protein profiles such as those in presurgical and postsurgical
sera within one patient would facilitate identification of biomarkers since the variability
of serial protein profiles within one patient is smaller than that between groups.
In this study, we examined serum proteins with differential levels in postsurgery
compared with those in presurgery after the removal of aneurysmal tissues in abdominal
aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA) patients in order to identify
potential serum biomarkers for AAAs and TAAs.

Results

A proteomic approach with an isobaric tag for relative and absolute quantitation (iTRAQ)
labeling followed by nano liquid chromatography (nanoLC)-matrix-assisted laser desorption
ionization (MALDI)-time of flight (TOF/TOF)-tandem mass spectrometry (MS/MS) was used.
In the sera of patients with AAAs and TAAs, a total of 63 and 71 proteins with differential
levels were further narrowed down to 6 and 8 increased proteins (≧1.3 fold, postsurgical
vs. presurgical) (p < 0.05, patient vs. control) and 12 and 17 decreased proteins (< 0.77 fold, postsurgical vs. presurgical) (p < 0.05, patient vs. control) in postsurgical sera compared with those in presurgical sera, respectively.
All of the increased proteins in postsurgical sera of both AAA and TAA patients included
several known acute-phase proteins. On the other hand, in the decreased proteins,
we found intriguing molecules such as α-2-macroglobulin, gelsolin, kallistatin, and
so on. Among them, we confirmed that kallistatin in both AAA and TAA patients and
α-2-macroglobulin in TAA patients showed decrease levels in postsurgical sera similar
to those in control sera by Western blot analysis with other sera from AAA and TAA
patients.

Conclusions

Taken together, our findings suggest that Kallistatin and α-2-macroglobulin are potential
serum biomarkers for both AAA and TAA and TAA, respectively.